Re: [PATCH v1 03/11] fs/proc/vmcore: disallow vmcore modifications after the vmcore was opened

[Baoquan He <bhe@redhat.com>]

On 10/25/24 at 05:11pm, David Hildenbrand wrote:
......snip...
> @@ -1482,6 +1470,10 @@ int vmcore_add_device_dump(struct vmcoredd_data *data)
>  		return -EINVAL;
>  	}
>  
> +	/* We'll recheck under lock later. */
> +	if (data_race(vmcore_opened))
> +		return -EBUSY;

As I commented to patch 7, if vmcore is opened and closed after
checking, do we need to give up any chance to add device dumping
as below? 

fd = open(/proc/vmcore);
...do checking;
close(fd);

quit any device dump adding;

run makedumpfile on s390;
  ->fd = open(/proc/vmcore);
    -> try to dump;
  ->close(fd);

> +
>  	if (!data || !strlen(data->dump_name) ||
>  	    !data->vmcoredd_callback || !data->size)
>  		return -EINVAL;
> @@ -1515,12 +1507,16 @@ int vmcore_add_device_dump(struct vmcoredd_data *data)
>  	dump->buf = buf;
>  	dump->size = data_size;
>  
> -	/* Add the dump to driver sysfs list */
> +	/* Add the dump to driver sysfs list and update the elfcore hdr */
>  	mutex_lock(&vmcore_mutex);
> -	list_add_tail(&dump->list, &vmcoredd_list);
> -	mutex_unlock(&vmcore_mutex);
> +	if (vmcore_opened) {
> +		ret = -EBUSY;
> +		goto out_err;
> +	}
>  
> +	list_add_tail(&dump->list, &vmcoredd_list);
>  	vmcoredd_update_size(data_size);
> +	mutex_unlock(&vmcore_mutex);
>  	return 0;
>  
>  out_err:
> -- 
> 2.46.1
>